Theft alarm



J. M. PARKS Dec. l8, 1936.

THEFT ALARM Filed Deo. 16, 1935 Inventor J/M. PI/{ Patented Dec. 8, 1936UNITED STATES PATENT OFFICE THEFT ALARM James M. Parks, Topeka, Kans.

Application December 16, 1935, Serial No. 54,544

11 Claims. (Cl. 116-94) This invention relates to burglar alarms of thatgeneral class operated by the power of a spring or equivalent deviceupon the release or severance of, or a pull on, a cord extending fromthe alarm device to the door, window or other movable part of thebuilding or structure for protection, and my object is to produce analarm device of the character indicated which can be easily and quicklyapplied in operative position and will be dependable in operation, andwhich embodies the desirable features of simplicity, strength,durability and cheapness of construction, and is of such size, lightweight and compactness as to be conveniently carried in a coat pocket.

With the general object indicated in view, the invention consists incertain novel features of construction and organization of parts ashereinafter described and claimed; and in order that it may be fullyunderstood reference is to be had to the accompanying drawing, inwhich:-

Figure 1 is a perspective view of an alarm device embodying theinvention.

Figure 2 is a top plan view of the same, broken away to disclose thespring element.

Figure 3 is an end view with a striker in impact position.

Figure 4 is a cross section on line IV-IV of Figure 1.

Figure 5 is a fragmentary vertical section to disclose the operative anddetachable relation between the shaft to be turned by the spring and thelocking key therefor for dislocation by a sufcient pull on the cord orfollowing the release or cutting thereof.

Referring now to the detail construction of the device, a supportpreferably in the form of a sheet metal or equivalent housing, comprisesan in- Verted U-shaped frame I, having foot portions 2, a base 3connected at its ends to and underlying the foot portions, and two sides4 against opposite side edges of the frame I and the base 3, the sideshaving inturned marginal flanges 5 embracing the base and top portionsand the vertical portions which constitute the ends of the housing, theparts being secured together as a unit by bolts 6 and nuts 1.

Extending through the housing and journaled in the ends thereof, is ashaft 8 provided at one of its extremities with a cross-head 9, and atthe other end with a diametric notch I0, and at the end of the housingin proximity to said shaft notch, a cam II is provided for a purposewhich hereinafter appears, the cam being in fixed relation to thehousing. Any suitable or conventional method may be resorted to forpreventing endwise play or shifting of the shaft 8. As shown, it isembraced by a sectional shaft I2 for abutment against the inner sides ofthe ends of thehousing, cotters I3, or the like, extending through shaft8 and the sections of shaft I2 to secure the parts f; together as aunit. A spiral spring I4 fits around the shaft and at one end is securedto the latter or to the adjacent Cotter. The opposite end of the springis fastened to the housing in any suitable manner, but preferably byextending it 10 up to and across the housing between the top thereof andthe sides, and providing it with a hook terminal I5 for firm anchoragebetween the opposed parts of the top and abutting side of the housing.15

A pair of similar equi-sized strikers or clappers I6, preferably ofsemi-disk form, are fitted against the outer side of and respectivelypivoted at I'I to the shaft cross-head 9 near its opposite ends, thearrangement being such that each rotation of the 1 shaft in thedirection indicated by the arrow in Figure 3, shall cause the strikerslto successively function, the arcuate edge of each, striking withconsiderable force because the power of the stroke, due to the speed ofrotation, is augmented by that of centrifugal force, as each striker,not only travels around the axis of shaft 8, but swings around itsrespective pivotal point. The object struck by the strikers may be abell, a pan, part of a bed frame, or any other resounding support, butfor compactness, and to avoid marring finished woodwork, it is desirableto employ a resilient plate to receive the strokes of the striker. Sucha plate I8, is shown fastened toand projecting laterally from the footunderlying the cross:- head, it being apparent that immediatelyfollowing impact of a striker, the latter, due to the uninterruptedrotation of the cross-head, swings upwardly on its pivot or in thereverse direction to its centrifugal travel, so that it shall slide or.4:0 drag over and pass out of Contact with the plate before the secondstriker engages the latter. The employment of a resilient plate slightlyarched, guards against chance of the strikers locking, and insures agreater volume of sound, the sound effect being akin to that of amachine gun.

One of the pivots Il' is extended to serve as a crank handle forconvenience in rotating the shaft to rewind the spring. When about fully.50 rewound, and with the notch I6 facing upward, a key I9 is fitted atits lower lend in the notch, the key having a shoulder 28 to rest uponthe shaft back of the notch. A cord 2I is attached to the key and run toa door, window or the like y theV ambit of the prior art.

of the' buildin-g or structure to'be protected, the cord being undersufficient tension to prevent the spring, by unwinding action, frombringing the key against the cam ll. By arranging the cord to hold thekey in approximately vertical position, and the cord so that it cannotinitially exert a pull endvvise of the key, it will be obvious that aslight pull on the key caused by sagging of or Wind pressure on thecord, Will not withdraw the key and result in sounding an alarm, butthat any pull on the cord sufcient to turn the shaft against theresistance of the spring iii, enough to dispose the key in approximateend- Wise alinement with that portion of the oord running directly fromthe key, Will result in the dislocation or Withdrawal of the key fromthe notch and thus leave the spring free to revolve the shaft. It Willalso `be apparent rthat the breaking, cutting or detachment of the cordfrom Vthe structure protected, will remove restraining force from thespring, and'that immediately thereafter, it will cause the key to engagethe cam and be forced outward thereby from the notch, thus leaving thespring free to revolve the shaft and sound the alarm until the power ofthe former is spent. As in rewinding the spring the strikers drop asthey pass dead center their respective pivotal points-it is desirablethat the plate I shall project beyond the opposite side of the housingfrom its arched or resonant end, and thus protect the surface of thesupporting bed or the like, from injury by the strikers during therewinding operation of the spring.

From the above description, it Will be apparent that I have produced aconstruction embodying all of the features of advantage set forth as desirable and While I have described and illustrated the preferredconstruction, it is to be understood that I reserve the right to allchanges within the spirit of the invention and Without I claimz- Y l. Inan alarm device, a support, a shaft journaled therein, means forrotating the shaft, a key detachably mounted on the shaft, a cordattached to the key for restraining the shaft from operation by saidmeans, a striker rotatable with and pivotally connected to the shaft ata point displaced with respect to the axis of the shaft, and means foreffecting dislocation of the key relative to the shaft under rotation ofthe latter by the first-named means, When the shaft is free ofYrestraint by the cord.

2. In an alarm device, a support, a shaft journaled therein, means forrotating the shaft, a key detachably mounted on the shaft, a cordattached to the key for restraining the shaft from operation by saidmeans, a striker rotatable with and pivotally connected to the shaft ata point displaced With respect to the axis or" the shaft, and a cam inthe path of rotation of the key by the said means, When the shaft isfree of restraint by the cord.

3. In an alarm device, a support, a shaft journaled therein, means forrotating the shaft, a key detachably mounted on the shaft, a cordattached to the keyfor restraining the shaft from operation by saidmeans, a striker rotatable With and pivo-tally connected to the shaft ata point displaced With respect to the axis of the shaft, and a cam fixedwith relation to the support and in the path of rotation of the key,when the shaft is free of restraint by the` cord.

4. In an alarm device, a support, a shaft jou.'-

naled therein, means for turning the shaft in one direction, a strikerrotatable With the shaft, a key detachably secured to the shaft, and acord connected to the key eccentrically of the shaft and normally undertension to prevent operation of the shaft byl said means, and adaptedwhen pulled With sufficient force, to apply pressure laterally on andturn the shaft in opposition to said means and then disengage the keyfrom the shaft by causingr endvvise movement of the key radially of theshaft.

5. In an alarm device, a support, a shaft jour naled therein, means forturning the shaft in one direction, a pin eccentrically carried by theshaft vand forming a handle for rotating the shaft against the reactionof said turning means, a striker pivotally supported on said pin forswinging movement independently of rotation of the shaft, a keydetachably secured to the shaft, and a cord connected to the keyeccentrically of the shaft and normally under tension to preventoperation of the shaft by said means,vand adapted when pulled withsufficient force, to apply pressure laterally on and turn the shaft inopposition to said meansand then disengage the key from the shaft bycausing endwise movement of the key radially of the shaft.

6. In an alarm device, a sup-port, a shaft journaled therein, providedwith a radial notch and a striker, means tending to revolve the shaft inone direction, a key standing upright on the shaft and engaging thenotch thereof, and a cord connected to the key eccentrically of theshaft and normally under tension to Vprevent operation of the latter andadapted under sufcient increase of tension, to apply pressure laterallyon and turn the/shaft in oppositionk to said means toeffect endvviseWithdrawal of the key from said' notch.

7. In an alarm device, a housing, a cam at one end thereof, a shaftjournaledin the housing and projecting through the ends thereof, aspiral spring surrounding the shaft and in fixed relation at its ends tothe shaft and housing respectively, a key detachably carried by theshaft, a cord attached to the key and, when under tension, causing thelatter to hold the shaft against rotation by said spring, the key, When`relieved of restraint by the cord, being caused in turning with theshaft, to engage and be dislocated from the shaft by said cam, and astriker rotatable With the shaft.

8, In an alarm device, a housing, a shaft journaled in and projectingbeyond the ends of the housing, a spiral spring encircling the shaftWithin the housing and secured at its oppositeV ends respectivelyto theshaft and the housing, a crosshead on one end of the shaft, a pair ofsemicircular strikers pivoted to the cross-head at opposite ends thereofand adapted for independent swinging movement relative to the crosshead,a key to engage and hold the shaft against 'operation by the said springwhen under tension, means for rst applying force laterally on the key tocause it to turn the shaft in opposition to the spring, and thenendvvise on the key to pull it out of engagement with the shaft, andmeans for tripping the key from the shaft when the latter is turned bythe spring when freed for action by removal of the restraint ofthe meansfor appying force laterally on the key.

19. In an alarm device, an alarm mechanism, aresiliently-actuated'rotatable shaft to effect operation of the alarmmechanism, a flexible member constantly tensioned by the `reaction ofthe resiliently-actuated rotatable shaft and holding the shaft againstrotation, and a key connecting the iiexible member to theresiliently-actuated rotatable shaft and releasable on predeterminedmovement of the flexible member to free the resiliently-actuated shaftfor rotation, said shaft being rotatable through at least an arc greaterthan 360.

10. In an alarm device, an alarm mechanism, a resiliently actuatedslotted rotatable shaft to effect operation of the alarm mechanism, aflexible member constantly tensioned by the reaction of theresiliently-actuated rotatable shaft and holding the shaft againstrotation, and a key connecting the flexible member to the shaft by beingdetachably received in the slot of said shaft, said key being Withdrawnfrom the slot on predetermined movement of the flexible member and saidshaft being rotatable through at least an arc greater than 360.

11. In an alarm mechanism, a support, a shaft journaled therein, meansapplying a yielding force tending to revolve the shaft in one direction,a striker revolvable With and around the shaft and also bearing apivotal relation thereto at a point offset relative to the axis of theshaft, and a flexible member normally restraining the shaft againstmovement but bearing a severable relation to the shaft to release samefor operation.

JAMES M. PARKS.

